The present invention relates generally to pallets used to support and transport a load of packages, and, in particular, to systems and methods for producing a disposable and/or recyclable pallet.
Pallets are typically used to support a load of packages, allowing the load to be lifted and transported by a lift truck such as a forklift. Several layers of packages may be loaded onto a pallet, and the load may then be secured around its circumference using, for example, flexible wrap or shrink wrap in order to stabilize the load on the pallet.
Some pallets have a platform upon which the packages are loaded and a base having channels adapted to receive the xe2x80x9cforksxe2x80x9d of a forklift. These pallets, hereinafter referred to as xe2x80x9cplatform-type palletsxe2x80x9d, are typically constructed from wood or plastic, and may be re-used multiple times. Disadvantages to using platform-type pallets involve the cost of producing the pallet, space required for and cost of storing the pallets, cost of shipping the pallet and its load to their destination, and cost and inconvenience of shipping the pallet back from its destination so it may be reused. The shipping costs are even more significant for relatively heavier pallets (e.g., wood pallets). Due to weight restrictions, the amount of product that can be shipped with the relatively heavier pallets is reduced. Furthermore, while these pallets are generally reusable, they are subject to breakage (especially wood pallets).
A relatively thin and lightweight alternative to a platform-type pallet is known as a xe2x80x9cslip sheetxe2x80x9d or xe2x80x9cslip palletxe2x80x9d. Referring to FIG. 1, a conventional slip pallet 10 may be, for example, a thin sheet of lightweight material such as plastic having one or more extending edges 12. The slip pallet 10 is loaded with packages 20 and the packages are usually wrapped around the circumference of the load (i.e., around a vertical axis) in order to stabilize the load 22. A specially adapted lift truck 24 grasps an edge, e.g. 12, of the slip pallet 10, pulls the slip pallet 10 onto a platform 26, and then lifts and transports the load 22 as desired. As the load 22 is lifted and transferred onto the platform 26, the weight of the load 22 shifts from the leading end 14 to the opposite (trailing) end 16 (as indicated by xe2x80x9cL1xe2x80x9d and xe2x80x9cL2xe2x80x9d), possibly damaging packages (e.g., 20a, 20b) located on the lowermost layers 18 on these ends 14, 16. The greater the lift angle xe2x80x9cAxe2x80x9d, the greater the weight xe2x80x9cL2xe2x80x9d exerted on the packages (e.g., 20b) located on the trailing end 16, especially those on the lowermost layers 18.
Using either a platform-type pallet or a slip pallet, additional damage may occur to the lowermost layers of packages during shipping due to vibration and jostling of the load.
High-speed packaging operations often use an automated system for xe2x80x9cpalletizingxe2x80x9d a load of packages which is typically referred to as a xe2x80x9cpalletizerxe2x80x9d. The term xe2x80x9cpalletizingxe2x80x9d as used throughout this application refers to arranging a plurality of packages (which includes any type of container, product, etc.) into a desired pattern (typically, but not necessarily having a square or rectangular xe2x80x9cfootprintxe2x80x9d) to form a xe2x80x9cpalletized tierxe2x80x9d. The term xe2x80x9cpalletized tierxe2x80x9d as used throughout this application refers to a single layer of adjacent packages arranged into a desired pattern. The term xe2x80x9cloadxe2x80x9d as used throughout this application refers to a stack of palletized tiers.
Examples of conventional palletizer systems are the 920-series palletizers manufactured by Alvey Systems, Inc., 9301 Olive Boulevard, St. Louis, Mo., 63132 (see xe2x80x9cwww.alvey.comxe2x80x9d); or the 520-series palletizers manufactured by Mectro/Emmeti USA, 101 Sherwood Drive, Boalsburg, Pa. 16827. An example of a conventional palletizer system 300 is schematically shown in FIGS. 7 and 8.
With reference to FIGS. 7 and 8, a conventional palletizer system 300 may include an infeed conveyor 302 and an output conveyor 398. As used herein, the term xe2x80x9cdownstreamxe2x80x9d generally refers to directions of conveyance away from the infeed conveyor 302 and/or toward the output conveyor 398. The term xe2x80x9cupstreamxe2x80x9d generally refers to directions of conveyance toward the infeed conveyor 302 and/or away from the output conveyor 398. The terms xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d do not necessarily refer to particular physical directions, since a package or load may change directions while traveling xe2x80x9cupstreamxe2x80x9d or xe2x80x9cdownstreamxe2x80x9d depending on the physical layout of the system 300. The term xe2x80x9clateralxe2x80x9d (or xe2x80x9claterallyxe2x80x9d, etc.) refers to directions of conveyance which are generally perpendicular to an xe2x80x9cupstreamxe2x80x9d or xe2x80x9cdownstreamxe2x80x9d direction. In FIGS. 7 and 8, exemplary downstream directions are shown by arrows with reference numeral xe2x80x9c301 xe2x80x9d exemplary upstream directions are shown by arrows with reference numeral xe2x80x9c303xe2x80x9d, and exemplary lateral directions are shown by arrows with reference numeral xe2x80x9c305xe2x80x9d.
As shown in FIGS. 7 and 8, the infeed conveyor 302 conveys packages 304 in a longitudinal (and possibly somewhat vertically declined), downstream direction 301 to a palletizing station 306 at which packages 304 may be arranged into a palletized tier 370 of adjacent packages 304. The palletizing station 306 may include a first conveyor portion 308 having a plurality of guide slats 310 mounted on a conveyor 312 such as, for example, a plurality of rollers 314. Specifically, each of the guide slats 310 may be slidably mounted between a pair of rollers 314. A guide slat control mechanism (not shown, but known in the art) may be adapted to slide the guide slats 310 laterally 305 in order to guide each of the packages 304 laterally 305 (FIG. 7) and downstream 301 to a desired location on the second conveyor portion 320.
The second conveyor portion 320 may comprise a re-orientation mechanism 322 which is adapted to re-orient certain packages (e.g. 304a, FIG. 7) generally perpendicularly to a package""s infeed orientation in order to create a desired palletized tier pattern. The re-orientation mechanism 322 may comprise, for example, several package turning devices 324,325 which are adapted to contact particular packages (e.g., 304a) while being conveyed downstream in order to turn the packages 90 degrees from their infeed orientation (see packages 304 on infeed conveyor 302, FIG. 7). A palletizer system 300 may be adapted to create a number of different palletized tier patterns with packages 304, as is well-known in the art. The pattern shown in FIGS. 7 and 8 (see the palletized tier 370) is merely exemplary of a desired pattern. The packages 304 may be conveyed downstream past the re-orientation mechanism 322 by any conventional conveyor 326 such as rollers 314, belts, chains, pusher bar assembly (described below) or the like and arranged into a loosely-formed tier 328 at the second conveyor portion 320. A stopping device 330 such as a retractable elongate plate or the like may be provided which is adapted to periodically halt the downstream flow of packages 304 in order to divide the packages into tier-sized groups and to longitudinally tighten up the loosely-formed tier 328.
The tier 328 may then be conveyed downstream by any conventional conveyor 331 such as rollers 314 to a third conveyor portion 332. As shown in FIG. 7, the palletizing station 306 may include lateral guides 334, 336 which are adapted to gradually laterally 305 guide the packages 304 into a more tightly-formed tier 340 at the third conveyor portion 332. The lateral guides 334, 336 may be comprised of a plurality of rollers 338 or the like as shown in FIG. 7 in order to minimize friction between the guides 334, 336 and the packages 304 as the packages are being conveyed downstream. A pusher bar assembly 342 or other type of conveyor (e.g., belt or rollers) may be provided at the third conveyor portion 332 in order to convey the tier 340 (FIG. 7) downstream from the palletizing station 306 to a stacking station 350. As best shown in FIG. 8, the pusher bar assembly 342 may comprise a pair of revolving pusher bars 344, 346 which may be mounted on an endless chain, belt, or the like, and translated along a path 348. The pusher bars 344, 346 may be mounted generally diagonally opposite one another as shown in FIG. 8 so that one of the pusher bars (e.g., 344) may serve as a stopping device as shown in FIG. 7 in order to temporarily halt the downstream flow of packages until the entire tier 340 is within the third conveyor portion 332. When the entire tier 340 is within the third conveyor portion 332 as shown in FIG. 7, the first pusher bar 344 may be translated along the path 348 (FIG. 8) up and away (upstream) from the stacking station 350 while the second pusher bar 346 is translated along the path 348 down and toward (downstream) the stacking station 350. The second pusher bar 346 may then contact the tier 340 and push it downstream to the stacking station 350. The second pusher bar 346 may then serve as a stopping device in order to temporarily halt the downstream flow of packages until another palletized tier is within the third conveyor portion 332.
As best shown in FIG. 8, at the stacking station 350, several palletized tiers (e.g., 370, 372, 374) may be stacked on one another and on a pallet 366 which may be, for example, a wooden pallet or a slip pallet (e.g., 10, FIG. 1) to form a load 376. As shown in FIG. 7, the stacking station 350 may include several guides 352, 354, 356 which, along with the pusher bar assembly 342, urge the packages 304 into a palletized tier 370 of adjacent packages 304. The stacking station 350 may include a retractable plate 360, FIG. 8, for arranging a palletized tier 370 thereon. The retractable plate 360 may be adapted to open (xe2x80x9cretractxe2x80x9d) and close as needed. Referring to FIG. 8, in order to assist in stacking the tiers (e.g., 370, 372, 374), the stacking station 350 may comprise a lift 362 (also referred to as a xe2x80x9cloweratorxe2x80x9d) which is adapted to lower the load 376 by the height of a tier xe2x80x9cT1xe2x80x9d as each subsequent tier is conveyed onto the load. The lift 362 may comprise a lift platform 364 which is translatable in a generally vertical direction xe2x80x9cY1xe2x80x9d (FIG. 8). As a palletized tier (e.g., 370) is positioned on the retractable plate 360, the lift platform 364 may be translated to a position (shown in solid lines in FIG. 8) directly beneath the plate 360. When the plate 360 opens or retracts, the palletized tier 370 may drop slightly onto a pallet 366 which has been placed on the lift platform 364. The lift platform 364 is then lowered in a vertical direction Y1 a distance T1. The plate 360 may then close and another palletized tier (e.g., 372) may be conveyed onto the plate 360. When the plate 360 is again retracted, the second palletized tier (e.g., 372) is placed on the first palletized tier (e.g., 370). In this manner, as many tiers as desired are stacked in order to form the load 376.
As shown in FIGS. 7 and 8, the palletizer system 300 may further comprise a pallet feeding station 368 which is adapted to store a supply of pallets 366 and transfer a pallet 366 as needed to the lift platform 364. The pallet feeding station 368 may be located, for example, adjacent to the lift 350. Each pallet 366 may be transferred to the lift platform 364 using a movable fork mechanism (not shown) or the like which is adapted to lift each pallet 366 from its storage location and transfer the pallet 366 to the lift platform 364. As noted above, a pallet feeding station may alternately be adapted to transfer slip pallets (e.g., 10, FIG. 1) to the lift platform 364. Slip pallets may be transferred to the lift platform 364, for example, manually or by using a mechanical transfer device (not shown).
The palletizer system 300 may further comprise a separator sheet assembly 378 which is adapted to store separator sheets (e.g., 380) and place a separator sheet 380 as needed on top of a palletized tier (e.g., 370, 372, 374) in order to separate the tiers. As best shown in FIG. 8, the separator sheet assembly 378 may comprise a translatable suction cup mechanism 382 or the like which is adapted to lift each separator sheet 380 and place it on a palletized tier.
After stacking, the palletizer system 300 may convey each completed load 376 downstream to a vertical wrapping station 384 in order to secure the load 376 around its circumference and stabilize the load 376 on the pallet 366, as is well-known in the art. In order to convey the load 376 downstream to the vertical wrapping station 384, the lift platform 364 may comprise a conveyor thereon (not shown, but typically comprised of one or more belts, chains, rollers, or the like). The lift platform conveyor may transfer the load 376 onto a conveyor 386 such as a plurality of rollers 387 or the like which convey the load 376 downstream to the vertical wrapping station 384.
As best shown in FIG. 8, the vertical wrapping station 384 may comprise a vertical stretch wrapper 388 which may be, for example, a conventional vertical stretch wrapper such as the Q-Series Stretch Wrapping System manufactured by Lantech, Inc., 11000 Bluegrass Pkwy., Louisville, Ky., 40299-2399 (see xe2x80x9cwww.lantech.comxe2x80x9d). As shown in FIG. 8, a conventional vertical stretch wrapper 388 may comprise at least one supply of flexible film 390 generally vertically-oriented along axis EE which may be slidably mounted on a stretch wrapper mounting portion 392. The flexible film 390 may be driven in a vertical direction Y1 along the stretch wrapper mounting portion 392. The vertical stretch wrapper 388 may also comprise a turntable 394 which is adapted to continuously rotate the load 382 in direction R3 around a vertical axis FF while the supply of flexible film 390 is unwound and moved in direction Y1. This may continue until the entire load 382 is wrapped around its circumference with as much flexible film 390 as is desired, thereby resulting in a wrapped load 396 on a pallet 366. As shown in FIG. 8, the turntable 394 may also comprise a conveyor 395 such as rollers or the like in order to convey each completed, wrapped load 396 downstream on an output conveyor 398 (which may also comprise rollers or the like) for pickup by a lift truck (e.g., 24, FIG. 1).
The invention is directed to a system and method for producing a load of packages supported by a disposable/recyclable pallet. The system may comprise at least one palletizing station comprising at least one palletizer producing a plurality of unwrapped palletized tiers of packages. The system may further comprise a horizontal wrapping station located downstream from a palletizing station. The horizontal wrapping station may comprise at least one horizontal stretch wrapper to produce a horizontally wrapped palletized tier of packages. A stacking station may be located downstream from and accessible to the horizontal wrapping station and at least one of the palletizing stations. The stacking station may comprise a lift which receives and stacks a plurality of unwrapped palletized tiers of packages on the horizontally wrapped palletized tier of packages. The system may further comprise a base applicator which fixedly applies a base to a bottom surface of the horizontally wrapped palletized tier of packages.
The method may comprise arranging packages into a plurality of unwrapped palletized tiers of packages at one or more palletizing stations. Then, at a horizontal wrapping station, at least one of said unwrapped palletized tiers of packages may be wrapped with flexible film around two horizontal axes and a second horizontal axis to produce at least one horizontally wrapped palletized tier of packages. Unwrapped palletized tiers of packages may then be stacked on the horizontally wrapped palletized tier of packages to produce a load of packages. A disposable/recyclable base may then be applied to a bottom surface of the horizontally wrapped palletized tier of packages to produce a disposable/recyclable pallet.